Severe weather incident in West Sussex was a tornado, say experts
The UK's Tornado and Storm Research Organisation (Torro) has completed its investigations into a severe weather incident which took place in West Sussex.
It has concluded that it was a T2 tornado, of track length around 3.5 km.
Houses were left with smashed windows and trees and brick walls were seen toppling over during the storm on 17th September 2023 at around 11:30pm.
The worst of the damage was centered around Cherry Croft in Littlehampton where many cars were damaged.
There was also some roof and tree damage and house windows were smashed.
According to Torro, the tornado appeared to start around the golf course at West Beach, Littlehampton and ended just north of Lyminster.
A T2 tornado is described as a moderate tornado with wind speeds of 73-92 mph.
Examples of the damage it can cause, as listed on Torro's website, are:
Heavy mobile homes displaced. Light caravans blown over
Garden sheds destroyed. Garage roofs torn away and doors imploded
Much damage to tiled roofs and chimneys. Ridge tiles missing
General damage to trees, some big branches twisted or snapped off, small trees uprooted
Bonnets blown open on cars
Weak or old brick walls toppled
Windows blown open or glazing sucked out of frames
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What is a tornado?
The Met Office describes a tornado as a rapidly rotating column of air that reaches between the base of a storm cloud and the Earth's surface.
They form in very unsettled weather conditions as part of severe thunderstorms. Many conditions need to be present for a tornado to form but, when these conditions are met, a violently whirling mass of air, known as a vortex, forms beneath the storm cloud.
A funnel cloud usually develops as the vortex forms due to the reduced pressure in the vortex. Strong inflowing winds intensify, and the spin rate increases as the vortex stretches vertically.
If it continues stretching and intensifying for long enough the vortex touches the ground, at which point it becomes classified as a tornado. The tornado then moves across the surface causing severe damage or destruction to objects in its path.
A tornado typically has the form of a twisting funnel-shaped cloud between the cloud base and the ground.
Sometimes the vortex can appear as a slender rope-like form, particularly when the tornado is weakening; sometimes a tornado can be almost invisible, observable by the debris thrown up from the surface. Tornadoes typically spin anticlockwise in the Northern Hemisphere (cyclonically).
Tornado facts:
1. Furthest distance
The greatest distance travelled by a tornado is 219 miles (352 km) from Ellington, Missouri to Princeton, Indiana on 18 March 1925.
2. The greatest number in 24 hours
The most tornadoes recorded in 24 hours is 175 on the 27-28 April 2011 in the USA.
3. Where do they form?
Most continents have regions with favourable conditions for tornado formation.
4. The greatest number in a month
The most tornadoes recorded in a single calendar month is 817 during April 2011 across the USA.
5. The most in a year
The most tornadoes during a single year is 1820 in 2004 across the USA.
6. The deadliest
The ‘Tri-State Tornado' on 18 March 1925 is known as the deadliest, killing 695 people. This tornado also travelled the furthest distance.
7. The strongest wind speed
It is impossible to know the exact strongest wind speed as they are only directly recorded in weaker tornados before weather instruments are destroyed. Doppler radars can give some remotely sensed wind speeds although these are not always accurate. Despite this, on 3 May 1999, a tornado in Oklahoma was measured to reach 302 mph, the highest winds ever found on the Earth’s surface. The most violent tornadoes have never been captured.
8. What is the costliest?
The costliest tornado was in Joplin, Missouri on 22 May 2011 with an estimated cost of $2.8 billion in damage.